The Sinorock® self-drilling hollow anchor bar solution uses the hollow threaded bar as a conduit for either air, water, or grout flushing mediums.The medium used is dependent on the ground conditions encountered. For example:rock would normally require air or water whereas soft or collapsing ground would require grout.

Grout Flushing
Then density of the grout is varied depending on the ground conditions; the greater
the need to support the annulus the thicker the grout required. Typically a W/C
ratio of between 0.7 and 0.4 would be used.
The flushing head transmits the rotary and percussive forces from the drilling
machine to the drill bit, while allowing continuous pumping of the flushing medium
through the Sinorock® Hollow Bar.

The flushing medium exits the apertures of the drill bit under pressure, creating a continuous pressure scouring action against the sides of the drill hole. This action exposes the harder parts of the hole while flushing and removing the softer parts to the surface therefore improving the surrounding ground.

When each bar has been drilled to depth it is withdrawn back up the mast and then redrilled in a reaming action to improve cuttings return and increase the scouring of the grout flush.

Scouring creates a very rough, irregular shaped grout body with a much greater bond and friction to the soil, providing greater pull-out resistance and lower settlement characteristics.